fix(igxSplitter): Assign pane props after zone is stable.

[MayaKirova]

Closes #15540

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them

[IMinchev64]

It seems that the splitter does indeed generate dynamically and the error is gone, however, I noticed that the splitter bars are initially positioned incorrectly (after the panes). If I try to move one of the bars then they get positioned properly. See attached screenshot:

[MayaKirova]

It seems that the splitter does indeed generate dynamically and the error is gone, however, I noticed that the splitter bars are initially positioned incorrectly (after the panes). If I try to move one of the bars then they get positioned properly. See attached screenshot:

HostBinding should reflect the order correctly now.